Wire drawing



Nov. 7, 1944. c. D. JOHNSON WIRE DRAWING Filed Feb. 5, 1945 Chofles Ddohnsbn byfmdw W ATTys.

Patented Nov. 7, 1944 WIRE DRAWING Charles D. Johnson, Worcester, Mass., assignor to Johnson Steel & Wire Company, Inc., Worcester, Mass, a corporation of Massachusetts Application February 5, 1943, Serial No. 474,856

8 Claims.

This invention relates to drawing wire.

Dies made of tungsten-carbide, which has a very high Rockwell hardness, are now commonly used for drawing wire in place of dies made from diamonds.

Some wire-drawing operations are carried out in such a way that the strain necessary to draw the wire through the die amounts to as much as 70% or more of the breaking strength of the wire. The strain on the wire when being drawn through a cold die is somewhat greater than when the wire .is being drawn through the same die while in a heated condition. Consequently where the wire drawing conditions are such that the force necessary to draw the wire through the die is as much as 70% of its breaking strength, the start of a wire-drawing operation with a cold die may result in breakage of the wire. For some wire-drawing operations, best results are secured ii the die is maintained in a heated condition, say at a temperature of from 350 degrees F. to400 degrees F.

The operation of drawing wire through a die generates heat. The amount of heat thus generated is sometimes sufllcient to overheat the die, and, therefore, it has been a common practice to cool a wire-drawing die by mounting it in a chambered holder through which cooling medium is circulated.

It i one of the objects of my invention to provide a wire-drawing apparatus with means whereby the die can be preheated to the proper wiredrawing temperature before the start oithe drawing operation, and can be maintained at such temperature whether the heat generated by the wire drawing operation is insuflicient for this purpose or is sufllcient in amount to overheat the die.

In order to give an understanding of the invention I have illustrated a selected embodiment in the drawing which will now be described after which the novel features will be pointed out in the appended claims.

In the drawing:

Fig. l is a diagrammatic view illustrating a wire-drawing apparatus embodying my invention.

Fig. 2 is a view of the die holder with the die therein.

Fig. 3 is a section on the line 33, Fig. 4.

Fig. 4 is a section on the line 4-4, Fig. 3.

In the drawing, the wire which is being drawn is indicated at 3, this wire being taken from a reel 4 and being drawn through the die by and wound on a drawing or accumulating drum I.

i The drawing die is indicated at 8 and it is mounted in a suitable holder I which is provided with an interior chamber 8 through which temperature-controlling liquid may be circulated, said chamber having aninlet pipe 9 leading thereto and a discharge pipe l0 leading therefrom.

it indicates a tank or vat containing temperature-controlling liquid l2 adapted to be circulated through the chamber 8 of the die holder I. For this purpose, both the inlet pipe 9 and the discharge pipe l0 extend into said tank and have their ends terminating within the body of liquid in the tank.

The liquid I2 i maintained at the desired temperature by means constructed to supply heat to the liquid in case the heat generated at the die by the wire being drawn therethrough is insufilcient to maintain the die at the required temperature, and to abstract heat from the liquid II in case the heat generated by the operation of the wire being drawn through the die is sufiicient to overheat the die.

l3 indicates a heating unit which is herein illustrated as an electrical heating unit and by which heat may be delivered to the liquid II. This heating unit is shown as connected to the heating circuit l4 and is controlled by a suitable thermostatic control element 15 which operates in a well-known way to maintain the circuit it closed as long as the temperature of the liquid [2 is below a predetermined point and to open said circuit whenever the temperature of the liquid I2 rises above a predetermined point. ll indicates a cooling coil which is immersed in the liquid i2 and which is adapted to have circulated therethrough a suitable cooling liquid, one example of which is brine. This coil i3 is connected at one end to a supply pipe l1 and at the other end to a discharge pipe It, said pipes leading to the source of supply for the cooling medium.

Situated in the pipe I1 is a pump indicated at l9 by which the cooling medium is caused to circulate through the coil [6. 20 indicates a thermostatic control for the pump l9. This control may be of any suitable or well-known type and is connected to the motor that operates the pump by means of circuit connections 22. The thermostatic control 20 is so constructed that so long as the temperature of the liquid l2 remains below a predetermined point, the pump I! will be inoperative, but as soon as the temperature of the liquid rises above such predetermined point, the motor of the pump will be set in operation through the action of the thermostat 20 thereby causing cooling medium to be circulated through the cooling coil I.

23 indicates a pump in the supply pipe I that operates to continuously circulate the liquid I! from the-tank ll through the chamber l of the die holder and back to the tank.

In using my improvements the heating element It will be set in operation before the wire to be drawn is threaded through the die 8, and this heating element will operate to heat the liquid l2, said heating element becoming automatically inoperative through the action of the thermostat II when the liquid l2 reaches the proper predetermined wire-drawing temperature.

The operation of the pump 23 in circulating the liquid l2 through the die holder causes the die to be heated.

When the die has been heated to the proper wire-drawing temperature, as determined by the temperature of the liquid l2. then the wire-drawing operation may be started by threading the end of the wire through the die 6 in usual manner and attaching such and to the drawing drum 5. When the drawing drum 5 is started in operation it will draw the wire through the die in a wellknown way.

The passage of the wire through the die and the consequent reduction in the diameter of the wire generates heat which tends to heat the die. If the heat thus generated is insufficient to maintain the die at the required wire-drawing temperature, the heated liquid l2 circulating through the chamber 8 of the die holder will make up such deficiency in heat and thereby maintain the die at this desired temperature.

n the other hand, if the wire-drawing operation is such that the amount oi heat generated by the passage of the wire through the die is sumcient to raise the temperature oi' the die above the desired wire-drawing temperature, then the excess heat thus generated in the die will be transferred to the liquid l2 which is circulating through the die holder with the result that the temperature of said liquid in the tank II will be gradually raised.

The raising of the temperature of the liquid I2 above the predetermined point or range will cause the thermostat l5 to open the heating circuit H and will cause the thermostatic control to set the pump I! in operation thereby circulating cooling medium through the cooling coil l6. This will result in reducing the temperature of the liquid II, or at least preventing the temperature of said liquid from rising further. This circulation of the liquid having a controlled temperature through the chamber 8 of the die holder will abstract excessive heat from the die and thus maintain the latter at a temperature within the desired temperature range.

The thermostatic control elements I! and 20 will be set to maintain the temperature oi the liquid l2 within any desired limits depending upon the character of the wire being drawn or the temperature at which it is desired to maintain the drawing die. For drawing some kinds of wire, a temperature range of the drawing die between 350 degrees F. and 400 degrees F. will be satisfactory, but this range can obviously be lowered or raised either by making proper adjustments in the thermostatic controls or using thermostatic controls designed to operate at the desired temperature range. It will be understood from the above that my invention provides means which is responsive to temperature changes in the die to lower the temperature of the liquid II by with- 7] drawing heat therefrom in addition to any heat which the liquid loses through radiation whenever the temperature or the die rises above the predetermined temperature range due to heat created by the wire drawing operation and to increase the temperature of the liquid by supp g heat thereto whenever the temperature of the die falls below said temperature range.

I claim: 1

l. A wire-drawing apparatus comprising a drawing die, a chambered holder therefore, means to circulate a heated liquid through the chamber of said holder, and means responsive to changes in the temperature of said liquid to maintain the temperature thereof within a predetermined temperature range which is best suited for the wire-drawing operation regardless of the amount of heat generated by the drawing of the wir through the die or the heat loss irom the die due to radiation.

2. A method of drawing wire which consists in preheating the drawing die to approximately the temperature best suited for the wire-drawing operation, drawing the wire through said preheated die and maintaining the die at approximately said temperature during the wire-drawing operation by withdrawing heat from the die in addition to that which it loses by radiation whenever the temperature of the die rises above said temperature due to heat generated by the wire drawing operation and supplying additional heat to the die whenever the temperature of the die drops below said temperature.

3. A wire-drawing apparatus comprising an apertured drawing die, a chambered holder therefor, means to circulate a heated liquid through the chamber of said holder, and means responsive to temperature changes in the liquid during the wire drawing operation to withdraw heat from said liquid in addition to that which it loses by radiation whenever the temperature of the die rises above a predetermined temperature range due to heat generated by the wire-drawing operation and to supply heat to the liquid whenever the temperature of the die falls below said temperature range.

4. A method of drawing wire which consists in circulating heated liquid around the die to preheat the same to a predetermined temperature which is best suited for the wire-drawing operation, drawing the wire through said preheated die, and maintaining the die within a predetermined temperature range during the wire drawing operation by withdrawing heat from said liquid and thereby from the die in addition to the heat lost by radiation whenever the temperature of the die rises above said predetermined range and supplying heat to said liquid and thereby to the die whenever the temperature of the die falls below said temperature range.

5. A wire-drawing apparatu comprising a drawing die, a chambered holder therefor, means to circulate a heating liquid through the chamber of said holder, and means responsive to temperatur changes in the liquid during the wiredrawing operation to withdraw heat from said liquid and thereby from the die in addition to that which it loses by radiation whenever the temperature of the die rises above a predetermined temperature range due to heat generated by the operation oi drawing the wire through the die and to supply heat to the liquid and thereby to the die whenever the temperature of the die tails below said temperature range.

in addition to that which it losesby radiation whenever the temperature of the die rises above a predetermined temperature range due to heat generated by drawing the wire through the die and to supply heat to the liquid and thereby to the die whenever the temperature of the die falls below said temperature range.

CHARLES D. JOHNSON. 

